Heat exchanger for dynamo-electric machinery



April 5, 1966 w. F. DAHLBERG 3,244,915

HEAT EXCHANGER FOR DYNAMO-ELECTRIC MACHINERY 4 Sheets-Sheet 1 INVENTOR. William F Dahlberg ATTORNEY Filed Oct. 24 1963 April 5, 1966 w. F. DAHLBERG 3,244,915

HEAT EXCHANGE 1R FOR DYNAMO-ELECTRIC MACHINERY Filed Oct. 24, 1963 4 Sheets-Sheet 2 INVENTOR.

Fig. William F Dahlberg ATTORNEY April 5, 1966 w. F. DAHLBERG 3,244,915

HEAT EXCHANGER FOR DYNAMO-ELECTRIC MACHINERY Filed Oct. 24, 1963 4 Sheets-Sheet 5 INVENTOR William F Dahlberg BY A TTORNE'V April 1966 w. F. DAHLBERG 3,244,915

HEAT EXCHANGER FOR DYNAMOELECTRIC MACHINERY Filed Oct. 24, 1963 4 Sheets-Sheet 4 F1 7 INVENTOR.

g- 6 BY William F Dahlberg A T TOPNE'V United States Patent F 3,244,915 HEAT EXCHANGER FOR DYNAMO-ELECTRIC MACHINERY William F. Dahlberg, Chicago, IlL, assignor to Goodman Manufacturing Company, Chicago, 111., a corporation of Illinois Filed Oct. 24, 1963, Ser. No. 318,551 3 Claims. (Cl. 31057) The present invention relates generally to .heat exchanges for dynamo-electric machinery and more particularly to apparatus for transferring heat from the interior thereof.

In dynamo-electric machinery such as wound rotor motors, a considerable amount of heat is generated in the rotor coils. Since these coils must be electrically insulated from each other and from the structural members of the motor, this heat is usually retained in the coil. Electrical insulating material used around the coil acts as a thermal barrier impeding the flow of heat away from the zone in which it is generated. This problem becomes especially acute in compact, high performance, explosion-proof motors.

Present designs of explosion-proof motors attempt to avoid contact between the potentially explosive atmosphere and localized hot spots" on the motor frame. It is evident that a step toward increased safety will result if the high temperature heat trapped in the rotor windings can be conducted away from the rotor and distributed throughout some other portion of the machine at a uniform but lower temperature.

Accordingly, an object of the present invention is to provide apparatus for conducting heat away from the zone of generation in the rotor windings of a dynamo electric machine. Another object is to provide apparatus for transferring heat from the rotor to an external heat sink. A further object is to provide apparatus for conducting heat from the armature of a motor to the body of machinery driven by the motor. Other objects and advantages will become apparent from the following description together with the drawings.

In the drawings:

FIGURE 1 is a plan view of an electrically powered machine of the type used in underground mining;

FIG. 2 is an elevation view, partly in section of a drive motor for the machine shown in FIG. 1;

FIG. 3 is a section view taken along the line 3-3 of FIG. 2;

FIG. 4 is a perspective view of a heat absorbing device with portions broken away to show the interior construction thereof;

FIG. 5 is a fragmentary view of a machine frame with portions broken away to show the location of fluid conduits;

FIG. 6 is a view taken along the line 6--6 of FIG. 5 showing the heat conductive relationship of the fluid conduits and machine frame; and

FIG. 7 is a wiring diagram indicating schematically how certain armature coils are connected to certain commutator bars.

Referreing now more particularly to the drawings, the numeral 10 refers generally to a self-propelled mining machine having a loading head 11, a mid-portion 12 and a discharge section 13. Tractor treads 14 and 16, driven by transmissions 17 and 18, support and propel machine 10 along the ground. Motors 19 and 21 are connected to transmissions 17 and 18 to furnish motive power for the machine. Other motors are mounted at various locations on the machine as required, such as motors 22 and 3,244,915 Patented Apr. 5, 1966 23 for driving the gathering head. The machine gathers broken and dislodged material onto a conveyor 24 by means of gathering arms 26 and 27 and delivers it to a haulage device at the rear, such as a shuttle car.

Referring now to FIGS. 2 and 3, the motor 19 is shown in greater detail. A shell 28 encloses a rotor 29 together with field coils 31, inter-pole windings 32, and brush rigging 33. Cooling fins 34 are located on shell 28 near field coils 31 to dissipate heat generated in the field coils.

Rotor 29 has a shaft 36 which extends through shell 28 to permit driving connections to be made to driven apparatus such as transmission 17. In some cases, the other end of shaft 36 may also be connected to a load such as pump 37. Coils 38 are secured in slotted armature section 39 by bands 41. The ends of each coil 38 are electrically connected to respective of bars 42, each of which is spaced from and electrically insulated from adjacent bars to collectively form a commutator 43. Brushes 4-4 and 46 are in electrical contact with respective of commutator bars 42 to provide an electrical circuit through various of coils 38 in the rotor windings.

Heat is generated in coil 38 as an undesirable byproduct, when rotor 29 is revolving in the magnetic field created by field coils 31. This heat is ordinarily trapped witihn the coil because the electrical insulation also acts as a thermal barrier. It is possible, however, for the heat to travel to commutator bars 42 following the path of the electrical current. This is particularly true if commutator bar 42 is at a lower temperature than the inner part of coil 38. The surface of each commutator bar 42 is subjected to an electric are twice each revolution thereby tending to raise its surface temperature above a value which would permit effective heat transfer from an inner portion of coil 38. It should be noted in FIG. 3 that each commutator bar 42 is out of contact with a brush for alternate periods of and 270 degrees or A and A of a revolution. The wiring diagram of FIG. 7 indicates that each coil which has a connection to a commutator bar within the 90 degree are also has at least one connection to a commutator bar in the 270 degree sector of the commutator. This means that every coil in the commutator has at least one connection to a bar within the 270 degree sector of the commutator. This also means that a path exists by which heat can flow from every armature coil to a bar in the 270 degree sector of the commutator whether the armature is turning or not. The numeral 47 indicates a heat exchanger device located closely adjacent the 90 degree sector of the commutator and capable of delivering a cooling stream of air around the 270 degree sector of the commutator. This cooling stream of air lowers the temperature of the commutator bars so that heat can flow out of the coils.

Referring now to FIG. 4, the heat exchanger device 4'7 is shown in more detail. A cover plate 48, forming a seal with motor shell 28, has a pair of upwardly projecting boses 49 and 51 forming a connection for conduits 52 and 53. Boss 49 has an interior passage 54 communicating with an upper chamber 56. Upper chamber 56 is connected to lower chamber 57 by a plurality of tubes 58. Four tubes 59 connect lower chamber 57 with the interior passage 61 in boss 51. Thus a coolant can flow through the tubes 58 inside shell 28 while maintaining an explosion-proof motor housing. Sidewalls 62 extend from upper chamber 56 to lower chamber 57 enclosing tubes 58 to form a passageway for air.

A small auxiliary motor 63 is mounted in a cylindrical duct 64 on spacers 66. An impeller 67 on the shaft of motor 63 urges air through the passageway in contact with tubes 58 and around the 270 degree sector of commutator 43 as indicated by arrows in FIG. 4. The air is cooled as it is circulated around tubes 58 and is re- Warmed as it cools the commutator bars 42. The heat generated in coils 38 flows to commutator bars 42 Where it is transferred to the air stream. The heat is then transferred from the air stream to the coolant by tubes 58, and the coolant is conducted away from the motor shell by conduit 52.

While I have shown such particulars as a fan driven by an auxiliary motor, and an air stream flowing around a portion of the commutator, it should be recognized that air or other dielectric fluid could be circulated by other means such as an impeller on the rotor shaft and that the fluid stream could be caused to flow around substantially the whole commutator as, for example, by means of vanes to direct the air stream.

As shown more particularly in FIGS. and 6, outbye conduits 52 are connected to tubes 68 and -69 which are welded to frame members 71 and 72 in order to transfer heat into the machine body 73 as a heat sink. After passing along a portion of machine body 73, tubes 68 and 69 are connected to a sump 74. Coolant is drawn from sump 74 through conduit 76 and pressurized by pump 37 for delivery to conduit 53 through conduit 77.

Thus, I have shown and described apparatus for conducting heat away from the armature coils, where it is generated, to a heat sink formed by the body of the machine driven by the motor. While I have shown and described a preferred embodiment of my invention, it should be recognized that various other forms exist Within the spirit of the invention and the scope of the appended claims.

I claim:

1. In electrically powered machinery having an armature and commutator enclosed within a shell, the improvement in heat dissipating apparatus comprising:

a heat exchanger disposed near said commutator within said shell; an auxiliary high speed motor and fan disposed within said shell and adapted to circulate air around said commutator and through said heat exchanger;

conduit means connected to said heat exchanger externally of said shell; and

a pump on said machinery connected to said conduit means adapted to circulate a coolant through said heat exchanger and the frame of said machinery.

2. The device of claim 1, in which said auxiliary high speed motor and fan are disposed within said shell with the rotative axis thereof normal to the axis of said commutator. I V

3. The device of claim 1, in which said auxiliary motor fan and heat exchanger are aligned within said shell with the rotative axis of said motor and fan normal to the axis of said commutator, and said frame member of said machinery is a heat sink and sump for said coolant.

References Cited by the Examiner UNITED STATES PATENTS 2,306,736 12/1942 Linville 310--57 2,460,752 2/1949 Jacobsen 31057 2,787,720 4/1957 Ethier et a1. 31057 MILTON O. HIRSHFIELD, Primary Examiner. L. L. SMITH, Assistant Examiner. 

1. IN ELECTRICALLY POWERED MACHINERY HAVING AN ARMATURE AND COMMUTATOR ENCLOSED A SHELL, THE IMPROVEMENT IN HEAT DISSIPATING APPARATUS COMPRISING: A HEAT EXCHANGER DISPOSED NEAR SAID COMMUTATOR WITHIN SAID SHELL; AN AUXILIARY HIGH SPEED MOTOR AND FAN DISPOSED WITHIN SAID SHELL AND ADAPTED TO CIRCULATE AROUND SAID COMMUTATOR AND THROUGH SAID HEAT EXCHANGER; CONDUIT MEANS CONNECTED TO SAID HEAT EXCHANGER EXTERNALLY OF SAID SHELL; AND A PUMP ON SAID MACHINERY CONNECTED TO SAID CONDUIT MEANS ADAPTED TO CIRCULATE A COOLANT THROUGH SAID HEAT EXCHANGER AND THE FRAME OF SAID MACHINERY. 